Progress in computers and communication equipments has been accompanied by improving performance in the large-scale integrated circuits (LSI) that are included therein as the main components. The improvement in LSI performance has been achieved by increasing the level of integration, i.e. microminiaturizing elements and increasing stacking number of interconnection. On the other hand, the increased cost of manufacturing LSIs with higher levels of integration does not meet the market demands for cost reduction.
For example, in the LSIs including the 5 to 10 layers of copper (Cu) interconnection, a manufacturing cost in the interconnection process has come to be a large proportion of overall manufacturing costs. Therefore, a technology for forming thin films used in Cu interconnection and the like at a low cost is required. JP-A 2003-273111 (Kokai) describes a method for providing a thin film of a desired form by filling concave portions provided in a substrate with a solution in which ultrafine particles of film material are dispersed, and then performing heat treatment.
According to this method, thin films can be formed easily without using vacuum equipment as in sputter and vapor deposition methods. It is therefore possible to reduce the manufacturing costs. However, in the case that high temperatures are required in the heat treatment to convert the fine particles to the thin film, there may be limits on the processes that can be applied. Moreover, if the concave portions are not filled uniformly with the ultrafine particles, areas of high resistance may be formed and/or a break in the interconnection may occur. Hence, a film forming method in which the concave portions can be filled uniformly with the ultrafine particles and the heat treatment can be performed at a lower temperature is required.